Long Term Evolution (LTE) is a radio technology designed to increase the capacity and speed of mobile telephone networks and provides for an end-to-end Internet Protocol (IP) service delivery of media. Currently, LTE comprises a set of enhancements to the Universal Mobile Telecommunications System (UMTS), which is described in a suite of Technical Specifications (TS) developed within and publicized by 3rd Generation Partnership Project (3GPP), with the most recent version of the 3GPP TSs being published in September 2010.
LTE, in part, provides for a flat IP-based network architecture designed to ensure support for, and mobility between, some legacy or non-3GPP systems such as, for instance, GPRS (general packet radio service) and WiMAX (Worldwide Interoperability for Microwave Access). Some of the main advantages with LTE are high throughput, low latency, plug and play, FDD (frequency-division duplex) and TDD (time-division duplex) in the same platform, improved end user experience, simple architecture resulting in low operating costs, and interoperability with older standard wireless technologies such as GSM (Global Systems for Mobile Communications), cdmaOne™, W-CDMA (UMTS), and CDMA2000®.
Many major carriers in the United States (US) and several worldwide carriers have started to convert their networks to LTE. However, there are some areas in which optimization would lead to a better user experience in LTE systems. One such area is with respect to the amount of signaling used to connect to the LTE system and to arbitrate the floor for media transmissions.
More particularly, at the end of a talk spurt by a user, several other users (e.g., of a talkgroup) may key a Push-to-Talk (PTT) button on their respective user equipment (UE) at roughly the same time to respond to the talk burst, thereby, moving their UE from an idle state to a connected state. To obtain the floor for media transmission, all UE wanting the floor request it explicitly on a signaling channel; and the UE receiving a grant is allocated a dedicated voice bearer for its media transmission to the other UE. Alternatively, all UE wanting the floor speculatively establish dedicated voice bearers and start transmitting on them, with the transmission itself acting as an implicit floor request. The UE whose floor requests are rejected tear down the established voice bearers. However, regardless of how floor control is carried out, the connected UE stay connected for some time (e.g. up to 10 s), including those that do not have dedicated bearers.
There are several problems with the above approaches. First, unless the UE explicitly prevents it, the connection request may start during the talk spurt of another user and use up resources, although the floor grant would likely fail. Moreover, the instantaneous signaling to establish connection and to set up and tear down voice bearers leads to temporary (wasteful) congestion, which can affect other users' attempts to connect to the system. In addition, the UE that attempted and failed to get the floor, will linger in connected state for approximately ten additional seconds, which can be very wasteful and create even more signaling, for example, if the UE need to hand over to neighboring cells during that time. Also, the UE that attempted and failed to get the floor effectively prevent other UE (which are in idle state) from getting the floor on a new keying of the PTT button because the already connected UE are able to send their floor request ahead of the idle ones. This all can affect the users' perception of the service and can create behaviors that favor extraneous, early keying, which in itself make things worse by placing even more UE in connected state.
Thus, there exists a need for methods of reducing set-up and floor control signaling in an LTE system.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of various embodiments. In addition, the description and drawings do not necessarily require the order illustrated. It will be further appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required.
Apparatus and method components have been represented, where appropriate, by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the various embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art, having the benefit of the description herein. Thus, it will be appreciated that for simplicity and clarity of illustration, common and well-understood elements that are useful or necessary in a commercially feasible embodiment may not be depicted in order to facilitate a less obstructed view of these various embodiments.